I have a lot of difficulty swallowing and pain in throat. i've had a ct scan of my neck, a barrium swallow, an ultrasound. if it were cancer, would it have shown up?

Likely ok: If you had all those studies done and they told you they are all normal, then i would have to say it is unlikely you have a carcinoma (in the areas they have looked at). Can have issues with swallowing for several different reasons besides something really bad.

Yes: With all that work up it should have showed up. Good luck.

Yes, it should be: You have had comprehensive tests. If it were cancer, yes, it would have shown up as abnormality on those tests and ultimately biopsy would be the one that confirms what it is. Discuss with your md. Good luck.

I would suggest you: See an ENT doctor and a neurologist. Ent's can do special barium swallowing studies by speech pathology to detect subtle functional swallowing issues. A neuroloist might explore myasthenia gravis, although pain does not fit that.